The present invention relates generally to glass supporting and conveying apparatus and, more particularly, to specially configurated, pivotal conveyor rolls especially adapted for use in press bending apparatus.
Generally, in the commercial production of curved or bent glass sheets in large quantities, such as is encountered in the mass production of glazing closures for automobiles and the like, the sheets are supported in a horizontal plane and advanced on externally driven roll-type conveyors in a horizontal path successively through a heating area, a bending area and a heat treating area for annealing or tempering the bent sheets.
The heated glass sheets are advanced from the heating furnace into the bending area and accurately located therein between complemental upper and lower shaping members by the engagement of the leading edges thereof with locating stops positioned in the path of movement of the advancing sheets. When properly oriented, the sheet is engaged along its marginal edge portions by the lower press member and lifted from the conveyor rolls for pressing between the complemental shaping surfaces of the press members to the desired curvature.
The lower or female press member is generally of ring-type construction having a shaping rail which engages only the marginal portions of the sheets. To permit the lower press members' shaping rail to be moved vertically above and below the conveyor, the shaping rail is comprised of a number of individual segments arranged in an end-to-end relation in the desired outline pattern with adjacent ends of the segments being spaced apart to permit the segments to move between the rolls of the conveyor. The shaping rails generally are of a substantially rectangular configuration in plan so that two sides of the shaping rail can be formed of continuous segments extending parallel to the rolls and the other two sides of the rail, which extend normal to the rolls, being formed of short segments spaced apart a distance only slightly greater than the diameter of the rolls. Accordingly, with a rectangular or substantially rectangularly configurated shaping rail, the spaces or gaps defined between adjacent segments can be held to a minimum with no significant, if any at all, sagging of the heat-softened glass into the spaces between adjacent segments. However, with the advent of more complex and elaborate glass shapes of widely varying outlines, the required similarly configurated shaping rails often have portions intersecting the rolls at acute angles whereby the spacing between adjacent shaping rail segments must be increased to the extent that they pose problems in accurately imparting the desired curvatures or shapes to the glass by the horizontal press bending procedure because of the tendency for the heat-softened glass sheets to sag between the widely spaced-apart shaping rail segments.